Interpretive Summary: Doppler weather radars primarily operate to detect precipitation and wind patterns in storms, but the detection of flying insects, birds, and bats can confound meteorological interpretation of the radar measurements. A study was conducted in the Lower Rio Grande Valley of Texas to determine the capability of Weather Service Radar (WSR-88D) to monitor migratory flights of corn earworms, a major economic pest of corn, cotton and other row crops. The aerial concentration of corn earworm-size insects measured by an entomological radar was positively correlated with WSR-88D reflectivity values. Wind velocity measured by instrumented weather balloons was positively correlated with WSR-88D estimates of wind speed and wind direction. The results reveal that WSR-88D measurements can be used to quantify migratory flight of corn earworms and other nocturnal insects, information which could benefit areawide pest management programs. Further, identification of migratory flights of corn earworm-size insects on WSR-88D radar measurements may lead to the development of mathematical analyses known as algorithms that increase the accuracy of WSR-88D measurements of reflectivity and wind velocity for weather analysis.

Technical Abstract:
Flying insects, birds, and bats contribute to radar reflectivity and radial velocity measured by Doppler weather radars. A study was conducted in the Lower Rio Grande Valley of Texas to determine the capability of Weather Service Radar (version 88D) (WSR-88D) to monitor migratory flights of corn earworm moths, Helicoverpa zea (Boddie). Reflectivity from airborne organisms is frequently detected by WSR-88D radars operating in sensitive clear-air mode during migratory seasons, often exceeding the lower threshold for precipitation mode (approximately 5 dBZ). The aerial concentration of corn earworm-size insects measured by a scanning X-band radar was positively correlated (r2 = 0.21) with WSR-88D radar reflectivity. Wind velocity measured by pilot balloons and rawinsondes was positively correlated with WSR-88D radar constant altitude plan position indicator estimates of wind speed (r2 = 0.56) and wind direction (r2 = 0.63). The results reveal that WSR-88D radar measurements of insect concentration and displacement speed and direction can be used to estimate the migratory flux of corn earworms and other nocturnal insects, information which could benefit areawide pest management programs. Further, identification of the effects of spatiotemporal patterns of migratory flights of corn earworm-size insects on WSR-88D radar measurements may lead to the development of algorithms that increase the accuracy of WSR-88D radar measurements of reflectivity and wind velocity for operational meteorology.